Such measuring systems are inserted, for example, in online-analyzers of process measurements technology. Examples are known from WO 2004/090513 A1 or DE 102 22 822 A1.
In the case of such measuring systems, radiation emitted by the radiation source, in given cases, as a beam or a reference beam formed with the assistance of optical elements, such as e.g. lenses, mirrors, beam dividers or optical fibers, is sent at least partially on the optical path through the flow through cell. In such case, there occurs an interaction between the radiation and the measured medium contained in the flow through cell. The interaction can lead especially to an absorption of at least part of the radiation, e.g. in a certain wavelength range. After passing through the flow through cell, the radiation changed by the interaction strikes the radiation receiver, which outputs a measurement signal dependent on the intensity of the striking radiation. From the measurement signal, deductions can be made concerning the interaction with the measured medium and, therewith, concerning the nature and/or composition of the measured medium, especially the concentration of an analyte in the measured medium.
The radiation can be led from the radiation source to the flow through cell and from the flow through cell to the radiation receiver by means of optical fibers.
For applications of such optical measuring systems in industrial biological, biochemical or biotechnological processes, it can be required that a sterile flow through cell be used. In biological, biochemical or biotechnological processes, the sterilizing of components, which are to come in contact with the process medium, especially with bacteria or yeasts used for biotechnological production, is frequently performed by irradiating with intensive gamma radiation. The gamma radiation can, however, lead to the damaging of other components of the measuring system, especially the radiation receiver or electronics arranged near the flow through cell. Unconditionally to be prevented, moreover, in biochemical, biological or biotechnological processes is cross contamination, which can occur, when a flow through cell is reused for measurements in different stages of a process or for measurements on different systems, i.e. different measured media.